This invention relates to belt powered machines, and more particularly to an electrostatographic toner image reproduction machine including a self-cleaning pulley device for reducing and minimizing contamination related problems in what is a contamination-proned environment.
Generally, the process of electrostatographic reproduction, as practiced in electrostatographic reproduction machines, includes charging a photoconductive member to a substantially uniform potential so as to sensitize the surface thereof. A charged portion of the photoconductive surface is exposed at an exposure station to a light image of an original document to be reproduced. Typically, an original document to be reproduced is placed in registration, either manually or by means of an automatic document handler, on a platen for such exposure.
Exposing an image of an original document as such at the exposure station, records an electrostatic latent image of the original image onto the photoconductive member. The recorded latent image is subsequently developed using a development apparatus by bringing a charged dry or liquid developer material into contact with the latent image. Two component and single component developer materials, particularly dry developer materials, are commonly used. A typical two-component dry developer material has magnetic carrier granules with fusible toner particles adhering triobelectrically thereto. A single component dry developer material typically comprising toner particles only can also be used. The toner image formed by such development is subsequently transferred at a transfer station onto a copy sheet fed to such transfer station, and on which the toner particles image is then heated and permanently fused so as to form a "hardcopy" of the original image.
The use of dry developer materials in electrostatographic toner image reproduction machines, obviously results in particularly toner particles from such materials becoming airborne inside and around the machines. It has been found that such airborne particles or contaminants are detrimental to the proper functioning of belt and pulley assemblies such as timing belt assemblies. For example, timing belt "jumping" has been identified as the primary field problem for a number of such machines. Normally, the airborne powdered material or toner particles settle on surfaces within the machine, including moving surfaces of moving belts that ride over pulleys. The belt surfaces thus move the particles onto the pulleys, where if not removed, the particles accumulate, and are then undesirably compacted thereon by the belt. In timing belt and pulley assemblies where precision is very important, such compacted build ups cause the belt to jump upon contact, thus resulting in improper functioning of the assembly.